Field of the Invention
This invention relates to a ball and socket type joint of the type used in vehicular steering and/or suspension applications and, more particularly, toward a ball joint assembly having an plastic bearing insert and snap ring retainer.
Related Art
Ball joints are typically used in vehicular applications where three dimensional movement of a wheel or other component is required. The ball joint provides an articulated connection needed when a vehicle is turning and the suspension is accommodating movement over rough terrain or subjected to cornering forces. In the normal course of operation, ball joints are subjected to very high stresses. Thus, their components must be manufactured from strong, usually heavy, materials, such as steel. However, the recent emphasis on reducing vehicular weight is driving design criteria toward ball joints with reduced weight through the incorporation of materials such as various engineering plastics.
Furthermore, there is a also a need to reduce both the cost and complexity of components used in motor vehicles. The ball joints are no exception. By manufacturing the ball joint assembly from fewer components, assembly operations are more efficient, thus translating into lower costs particularly where the components can be manufactured to a near-net shape using processes such as molding, rather than the use of extensive machining and grinding operations to form the net-shape components. Additionally, fewer components usually enable weight reduction. Therefore, multiple interests are served by reducing the number of components used in a ball joint assembly, as well as by the use of materials and methods of manufacture which achieve the objective described above.
FIGS. 15-16 depict typical prior art ball joint assemblies 210 as used in the application of stabilizer linkages 200. Heretofore, ball joint assemblies 210 have generally been made by first forming a sturdy, metallic housing 215 and inserting therein one or two bearings 220, 222 which form a sliding interface between the articulating ball end 225 of a stud 230 and the housing 215. A metal cover plate 235 and o-ring 245 are mechanically seated over the housing to retain the bearing components and the ball portion of the stud 230 inside the housing 215 and an elastomeric boot 240 is used to seal ball joint assembly 210 from the external environment, including dirt, salt and other known contaminants. Depending upon the number of bearing components, possible spring take-up members, and dust boot features, this assembly may require five or six separate components not including the ball stud. See for example the exploded view of FIG. 16 where a typical prior art ball joint assembly is shown requiring six separate components, not including the ball stud 230, as well as two clamps (not shown) used to secure the dust boot 240 to the housing 215 and stud 230.
In addition to the complexity noted with prior art ball joints and their manufacture, prior art ball joints also typically have a limited ability to resist pull-out forces, or forces which tend to cause the ball stud to pull out of the bearing socket. Generally, prior art ball joints of the sizes and types used for automotive vehicles are able to resist pull-out forces in the range of 350-650 lbs.
Thus, there is a continuing desire to further reduce the number of components and the complexity and cost of ball joint assemblies as used in vehicular applications for the purposes mentioned, as well as to improve the ability of these joints to resist pull-out forces.